The present invention generally relates to an apparatus for processing materials in powder or granular form (referred to as a granular material processing apparatus hereinbelow), and more particularly, to a sealing arrangement which is adapted to tightly close or seal gaps or clearances between a stationary container means, for example, a hopper for accommodating therein the granular material to be processed and a movable processing means, for example, a stirrer rotatably mounted within said hopper, in the filling or processing apparatus, for example, for pharmaceutical granular and powdery materials so as to prevent undesirable entry or mixing of foreign matters into the granular and powdery material being processed, through such gaps.
Conventionally, in a granular material filling or processing apparatus as referred to above, it has been generally so arranged that, for example, in the hopper for storing therein the granular and powdery material (referred merely to as granular material hereinbelow) and the stirrer for agitating the granular material accommodated in said hopper, a stirring or rotary shaft for supporting stirring blades of the stirrer extends through a side wall of the hopper, with the side wall being tightly closed or sealed by an ordinary packing member at such portion so as to prevent undesirable spilling or scattering of the granular material by the packing member thus provided.
However, in known arrangement as described above, there have been such disadvantages that, since metallic material, resinous material, felt, or the like are normally employed for the packing member, it has been difficult to fully eliminate troubles due to wearing of the packing member, or spilling of granular materials owing to deterioration of the packing member, etc., particularly with a possibility that particles or chips of the packing member are undesirably mixed into the granular material being processed due to abrasion or deterioration of such packing member. Thus the prior art arrangement has not been very satisfactory especially when the granular material to be processed is intended for pharmaceutical use.